Athel Pine (Tamarix Aphylla) NT Weed Risk Assessment Technical Report
Total Page:16
File Type:pdf, Size:1020Kb
Athel pine (Tamarix aphylla) NT Weed Risk Assessment Technical Report January 2014 www.nt.gov.au/weeds Athel pine Tamarix aphylla Please cite this report as: Department of Land Resource Management (2014). Athel pine (Tamarix aphylla) NT Weed Risk Assessment Technical Report, Department of Land Resource Management, Darwin. ISBN: 978-1-74350-050-7 Acknowledgments The NT Weed Risk Management (WRM) System was jointly developed by Charles Darwin University (CDU) and the Weed Management Branch, Department of Land Resource Management (DLRM); our thanks to Samantha Setterfield, Natalie Rossiter-Rachor and Michael Douglas at CDU. Project funding for the development of the NT WRM System, obtained by Keith Ferdinands and Samantha Setterfield, came from the Natural Heritage Trust. Our thanks to the NT WRM Reference Group for their assistance in building the NT WRM System and the NT WRM Committee for their role in building the system and their ongoing role in weed risk assessments. Cover photo (top): Cultivated athel pines growing near buildings. Cover photo (bottom): Athel pine infestation along the Finke River, NT. Final report compiled January 2014. Edited by Louis Elliott, Department of Land Resource Management. NOTE: Online resources are available at https://nt.gov.au/environment/weeds/list-of- declared-weeds-in-the-nt/athel-pine which provide information about the NT Weed Risk Management System including an explanation of the scoring system, a fact sheet and user guide, a map of the NT weed management regions and FAQs. Weed Management Branch contacts For more information or advice in relation to the identification, management or monitoring of weeds please contact the Weed Management Branch: Phone: (08) 8999 4567 Email: [email protected] Website: http://www.nt.gov.au/weeds The NT Herbarium can also provide plant identification advice Phone: (08) 8999 4516 Rangelands Division Department of Land Resource Management PO Box 496 Palmerston NT 0831 © Northern Territory of Australia, 2014 This product and all material forming part of it is copyright belonging to the Northern Territory of Australia. You may use this material for your personal, non-commercial use or use it with your organisation for non-commercial purposes provided that an appropriate acknowledgement is made and the material is not altered in any way. Subject to the fair dealing provisions of the Copyright Act 1968 you must not make any other use of this product (including copying or reproducing it or part of it in any way) unless you have the written permission of the Northern Territory of Australia to do so. 2 www.nt.gov.au/weeds Athel pine Tamarix aphylla Weed risk and Feasibility of Control results Table 1. Weed Risk and Feasibility of Control (FOC) results for athel pine (Tamarix aphylla). Weed Risk is calculated for the whole of the Northern Territory; FOC is calculated by Weed Management Region. Maximum score for Weed Risk and FOC is 1000. Each has three sections (A, B, C), with section scores expressed as a percentage. Weed Risk (NT) Band Very high Score 412 Note: For an explanation of how the Weed Risk and Feasibility of Control scores and bands are calculated, A. Invasiveness (%) 83 and for the Northern Territory Weed Management B. Impacts (%) 74 Regions, refer to www.nt.gov.au/weeds/risk. C. Potential distribution (%) 67 Feasibility of Control (by region) Weed Management Region Darwin Katherine Tennant Creek Alice Springs Band - - High Medium Score - - 251 125 A. # Control costs (%) - - 55 55 B. ## Current distribution (%) - - 100 50 C. Persistence (%) - - 46 46 # A high score indicates low control costs and contributes to a high Feasibility of Control. ## A high score indicates a restricted distribution and contributes to a high Feasibility of Control. Table 2. Broad management response recommended for athel pine (Tamarix aphylla) by Weed Management Region, according to Weed Risk and Feasibility of Control assessments. Feasibility of Control Very high–High Medium–Low Prevent movement; regional eradication; Targeted control (including biocontrol)/protect Very high contain regional spread; protect priority sites priority sites Prevent movement; contain regional spread; High protect priority sites Targeted control Medium Targeted control; improve general weed Improve general weed management management; monitor; protect priority sites Low Monitor; assist interested parties Assist interested parties Tennant Creek Region Alice Springs Region www.nt.gov.au/weeds Athel pine Tamarix aphylla 3 Background information Taxon Tamarix aphylla Synonyms Tamarix articulata, Thuja aphylla Common name Athel pine Other names Tamarisk, saltcedar, athel tree Family Tamaricaceae (tamarisk family) Lifeform Tree Environment Terrestrial Origin Northern Africa, the Arabian Peninsular, Iran and India. Legislation Declared in all other Australian states and territories. Declared Class A and Class B in different parts of the Northern Territory. The NT declaration zones for athel pine are available at: www.nt.gov.au/weeds/find/athelpine. Description Large, spreading tree up to 15 m tall. Athel pine is not a true conifer or pine, but its pendulous needles and branches give it the appearance of one. Salt secreting glands in the needles create a whitish coating giving the tree foliage a silvery grey appearance. Small, white and pink flowers occur in dense racemes. Habitat Dominates sandy riparian habitats in the arid zone. In the Northern Territory, it forms monospecific stands along rivers and adjacent fringing woodlands in the arid zone. It is spread by wind and floodwaters, and is able to establish on sandy soils free of other vegetation. Distribution There are large infestations present in South Australia, New South Wales, Queensland and Western Australia. In the Northern Territory athel pine is mainly found in the central region, where it was extensively planted in Aboriginal communities and at homesteads, bores and roadhouses as far north as the Barkly region. Extensive stands of athel pine are found on the Finke River system south of Alice Springs. Other Athel pine is recognised as a Weed of National Significance. Athel pine is also a significant invasive species in southern USA. Current situation in the NT In the Northern Territory (NT) athel pine is well established in the Finke River, this being the largest naturalised infestation in Australia. Infestations outside this core area, such as those found in Walker and Karinga Creeks, are smaller and of lower density, and as such have been prioritised for management. Historical and amenity plantings of athel pine are found throughout the southern region of the Territory. As these present potential for spread, their control and removal is also considered a management priority. 4 www.nt.gov.au/weeds Athel pine Tamarix aphylla Summary of Weed Risk and Feasibility of Control Weed RIsk A. Invasiveness: Intentionally introduced into Australia and widely planted for shade. Current infestations originate from trees planted around homesteads and communities. Seed viability is moderate (c. 22%), but a single tree is capable of producing enormous quantities of tiny seed (c. 500 000) which are principally spread by floodwaters. A major dispersal event occurred in the NT with the flood of 1974, with floods in later years aiding further establishment. It is also able to spread vegetatively—broken stem fragments can take root and are also spread by floods. People may continue to accidentally spread athel pine with heavy machinary such as graders. B. Impact: Forms monocultures which displace native vegetation, particularly the iconic river red gums (Eucalyptus camuldulensis) and coolibah (Eucalyptus microtheca) in central Australia. Athel pine extracts salt from the soil, causing salination affecting plant growth up to 50 m away. It lowers the water table, dry up waterholes, adds to sedimentation rates and can change the course of rivers. Only salt-tolerant herbs or grasses can grow under athel pine, so it reduces grazing area. Native birds, reptiles and insects are negatively impacted—athel pine flowers have no nectar, the trees do not provide hollows for nesting, and it is a poor source of food for invertebrates. A threatened species of brushtail possum is impacted. C. Potential distribution: Wide native and introduced range throughout arid and semi-arid zone, surviving in areas with rainfall as low as 100 mm/year. The climate for optimum growth is probably 350–500 mm/year. Particularly suitable vegetation types in the NT are arid and semi-arid riparian and wetland areas, due to dispersal by floodwaters and the close proximity of groundwater. Feasibility of Control A. Control costs Moderate. Athel pine is readily identifiable and infestations are generally accessible for treatment. However, the tree does not translocate chemical well. Chemical and labour costs are very high, especially for large infestations. B. Current distribution (NT) Large stands of athel pine exist on the Finke River system in the Alice Springs Region. In other parts of the arid and semi-arid NT, infestations tend to isolated. In these areas, isolated trees planted for amenity purposes continue to exist. C. Persistence Moderate. Seeds remain viable for a only a few weeks. However vegetative propagules can propagate even when there is no seed. The tree can live for at least several decades. General Management Recommendations Refer to the Weed Management Plan for Athel Pine (Tamarix aphylla). This can be found at www.nt.gov.au/weeds/find/athelpine. 5 www.nt.gov.au/weeds Athel pine Tamarix aphylla Weed Risk Assessment - Determinations A. INVASIVENESS Determination A1. What is the ability of the plant to establish amongst intact native environments? Very high A2. What is the reproductive ability of the plant? a) Time to seeding 2-3 years b) Annual production of viable seed per sq m or /plant High c) Vegetative reproduction Frequent A3. Do propagules of the plant have properties that allow them to be dispersed long-distance by natural means? a) Flying animals (birds, bats) Don't know b) Other wild animals Don't know c) Water Yes d) Wind Yes A4.